There are many applications in which it is necessary or desirable to connect cables or metal tubes buried within the foundation of a structure or located within an underground manhole or vault to equipment or apparatus located at substantial distance away from the point at which the cables or tubes emerge from the foundation, manhole or vault. A common practice is to place the cables or tubes within and along a hollow plastic, metal or concrete conduit, which itself may be cast within the foundation, manhole or vault, and, at the point at which the cables or tubes emerge from the conduit, to seal the openings or spaces between the cables or tubes and the conduit. The sealing of the conduit serves to minimize the entry of water or other liquids into the conduit and also to minimize or prevent penetration of the seal by underground pests such as rodents and insects. The rodent problems can be especially severe in the case of buried electrical and fiber optic cables.
The sealing of the openings or spaces between cables or tubes and the associated conduit as described hereinabove can generally be accomplished by the use of a standard sealing compound, for example, of the mastic type or, alternatively, by the use of commercially-available mechanical sealing assemblies. If a sealing compound is used, it is generally stuffed into the openings or spaces between the cables or tubes themselves and the conduit and allowed to harden. This technique has the disadvantage of being a permanent solution and thus may be impractical if it later becomes necessary to re-route or relocate the cables or tubes or to make other changes (e.g., repairs) to the cables or tubes. In these latter cases, destruction of the seal is generally necessary. This type of seal also falls short in its ability to resist penetration by rodents and other pests.
Commercially-available sealing assemblies generally take the form of a threaded fitting attached to the conduit, a rubber bushing through which the cables or tubes are end fed, and a threaded end cap which surrounds the rubber bushing and is screwed onto the fitting, causing the rubber bushing to compress around the cables or tubes and effect a seal between the cables or tubes and the conduit. This type of sealing assembly has the major disadvantage of requiring the cables or tubes to be end fed through the rubber bushing, an operation which can be a great inconvenience if the cables or tubes are to be fed to other than a nearby location, for example, to a location several hundred feet away from the point at which the cables or tubes emerge from the conduit. In addition, small openings or spaces between and around the cables or tubes themselves can still remain, enabling water or other liquids or pests to enter by way of these openings or spaces into the conduit.